In various sectors of the art there is a perceived need for being able, in case of necessity or emergency, or simply for convenience or for ecological reasons, to have available an auxiliary source of electrical energy.
Usually, such auxiliary sources of electrical energy consist of energy accumulators in the form of rechargeable batteries.
The charge capacity of such batteries varies according to whether they are destined for small power users or high power users.
Examples of small power users are cellphones, audio/video players (e.g. mp3 players, tablets) or electronic devices in general, lighting equipment, alarm services, emergency services etc.
Examples of high power users are motors in the automobile sector, but also in the motorcycle and cycle sector, etc.
In various situations, where an electrical energy distribution network is not available, for example in isolated locations far from centres of habitation, the problem of recharging batteries often arises, with the result that once the charge accumulated in them is exhausted, the batteries themselves become unusable.
Furthermore, in the mobility sector there is a particular perceived need to have available a “zero emission” energy source, i.e. one that is capable of making energy available without any release of polluting emissions.